TW202509670A - Substrate storage module and method - Google Patents

Abstract

A substrate storage module for use as an integral part of a lithographic apparatus comprising a controllable environment for protecting a plurality of substrates from ambient air. The substrate storage module comprises a plurality of substrate supports for receiving the substrates, and a vacuum system fluidly coupled to the plurality of substrate supports. The vacuum system is configured to individually clamp and release the substrates.

Description

Substrate storage module and method

The present invention relates to a substrate storage module and a method for storing substrates, particularly in the context of lithography apparatus and methods.

A lithography apparatus is a machine constructed to apply a desired pattern onto a substrate. A lithography apparatus may be used, for example, in the manufacture of integrated circuits (ICs). For example, a lithography apparatus may project a pattern from a patterning device (e.g., a mask) onto a layer of radiation-sensitive material (resist) disposed on a substrate.

The wavelength of the radiation used by the lithography apparatus to project a pattern onto a substrate determines the minimum size of features that can be formed on that substrate. Lithography apparatus using EUV radiation, which is electromagnetic radiation having a wavelength in the range of 4 nm to 20 nm, can be used to form smaller features on a substrate compared to conventional lithography apparatus (which may, for example, use electromagnetic radiation having a wavelength of 193 nm).

The maximum area of a patterned device that can be imaged onto a substrate using a lithography apparatus (i.e., the maximum image area) can vary between different lithography apparatuses. For example, some lithography apparatuses may only be capable of imaging an area of the patterned device that is less than or equal to half the maximum image area of other lithography apparatuses. A technique known as stitching can be used to overcome the limited maximum image area of some lithography apparatuses. Stitching includes performing at least two sub-exposures on adjacent areas of a substrate to form a combined image on the substrate. After performing the lithography exposures, the substrate undergoes an anti-etchant treatment including, for example, a baking process. In the case of stitched exposures, the baking process is delayed until each set of sub-exposures has occurred on all target areas of the substrate. A plurality of substrates to be lithographically processed as a group may be referred to as a batch. A delay may occur between a first set of sub-exposures of a first substrate in a run batch and a subsequent set of sub-exposures of a final substrate in the run batch. Lithographically exposed resist on the substrate may be susceptible to degradation during this delay.

For example, it would be desirable to provide a substrate storage module and method that prevents or mitigates one or more of the problems of the prior art identified herein or elsewhere.

According to a first aspect of the present disclosure, a substrate storage module is provided for use as an integral part of a lithography apparatus. The substrate storage module includes a controllable environment for protecting a plurality of substrates from ambient air. The substrate storage module includes a plurality of substrate supports for receiving the substrates. The substrate storage module includes a vacuum system fluidically coupled to the plurality of substrate supports, the vacuum system being configured to individually grip and release the substrates.

The substrate storage module advantageously provides a space in which substrates can be stored and protected from negative effects caused by the surrounding air after lithography exposure. For example, the substrate storage module can protect a substrate that has undergone a sub-exposure for an extended period of time during a stitched lithography exposure. The substrate storage module advantageously stores a plurality (e.g., at least eighteen) of substrates, making the substrate storage module suitable for storing substrates during a lithography process (e.g., involving eighteen or more substrates).

Conventional substrate storage modules rely on gravity to hold substrates in place against substrate supports. When conventional substrate storage modules are moved (e.g., to allow a robot to access stored substrates) and/or when mechanical vibrations are incident upon conventional substrate storage modules (e.g., due to movement of other components of a lithography apparatus), the stored substrates experience undesirable movement (e.g., rocking and/or sliding) from their original positions on the substrate supports. Due to frictional forces between the substrates and the substrate supports, the undesirable movement may damage the substrates and/or introduce substrate defects. Unwanted movement can cause damage to the substrate because the substrate is no longer level with the substrate support and/or may be misaligned with other components (e.g., a robot arm), which can cause the substrate to be bumped or dropped. The vacuum system of the present disclosure advantageously reduces the risk of stored substrates experiencing undesired movement by using vacuum (e.g., gas pressure) force to clamp and secure the substrate to the substrate support. The vacuum system advantageously allows each stored substrate to be clamped and released individually, thereby allowing one substrate to be removed or stored while preventing the other substrate from slipping. This is particularly advantageous in the context of performing stitched lithography exposures, where different substrates can be individually clamped or released at different times between sub-exposures. The vacuum system of the present disclosure advantageously allows the substrate support to be moved with greater acceleration and speed which reduces the risk of a stored substrate moving or falling off the substrate support. This in turn allows for greater throughput of substrates (e.g., greater throughput of substrates through a lithography exposure process).

The term "integral part" is intended to indicate a substrate storage module that remains connected to the lithography apparatus throughout operation of the lithography apparatus (ie, the substrate storage module cannot be removed from the lithography apparatus unless the lithography apparatus is powered off).

The substrate storage module can be configured as an integral part of the lithography equipment.

The controlled environment can be configured to protect at least eighteen substrates from ambient air.

A plurality of substrate supports may be configured to receive a substrate.

The plurality of substrate supports may include a coating configured to reduce friction between the plurality of substrate supports and the substrate.

The coating advantageously reduces frictional forces acting between the substrate and the substrate support. This in turn advantageously reduces the risk of damaging the substrate and/or introducing substrate defects compared to known substrate storage modules.

Each substrate support may include a coating.

The coating may comprise diamond-like carbon.

Diamond-like carbon has been found to be particularly effective in reducing friction between the substrate support and the substrate.

A plurality of substrate supports may be configured to be individually removable from the substrate storage module.

Having individually removable substrate supports advantageously allows each substrate support to be removed for maintenance or disposal without affecting the other substrate supports. For example, a substrate support may be defective, in which case a user may remove the defective substrate support from the substrate storage module and replace the defective substrate support with a spare functional substrate support. As another example, a substrate support may require maintenance, in which case a user may remove the substrate support from the substrate storage module for cleaning and/or securing prior to reinserting the substrate support. A plurality of substrate supports may be configured to be individually replaceable, such as in a manner similar to a cassette.

The vacuum system may include a sensing system configured to detect the presence of a substrate in a plurality of substrate supports.

The sensing system may include one or more pressure sensors in one or more vacuum lines of the vacuum system.

The sensing system advantageously indicates the number of substrates held by the substrate supports and indicates which substrate supports are free to receive substrates.

The substrate storage module may include a gas delivery system configured to provide gas flow across each substrate support within the substrate storage module.

The air flow over each substrate held by the substrate storage module advantageously reduces the risk of defect cross contamination between stored substrates.

The gas may comprise filtered air. The gas may comprise nitrogen. The gas may be inert.

The filtered air may include clean room air. The filtered air may include air having a particle cleanliness greater than that provided by ISO 14644 Class 1. The filtered air may include less than one particle per cubic meter, the particle having a size of about 0.1 µm or greater.

Filtering the air advantageously reduces the risk of contaminants being incident on the stored substrates.

Gases may contain low humidity.

The gas may have a humidity of about 50% or less. The gas may have a humidity of about 30% or less. The gas may have a humidity of about 10% or less. The gas may have a humidity of about 7% or less. The gas may have a humidity of about 1% or less. The gas may have a humidity of about 0%.

Providing an airflow with low humidity advantageously reduces the risk of degradation of stored substrates.

Gases can include very clean, dry air.

Very clean dry air may contain <1 ppbv TOCv, where TOCv represents total volatile organic compounds and ppbv represents parts per billion by volume. Very clean dry air may contain <1 ppbv TOCnv, where TOCnv represents total non-volatile organic compounds. Very clean dry air may contain <100 ppbv H ₂ O. Very clean dry air may have a particle cleanliness equal to or greater than ISO 14644 Class 2.

Very clean dry air has been found to be particularly effective in protecting stored substrates (e.g., photoresists of lithography substrates) from degradation, thereby improving the useful life of the substrates.

The gas delivery system may include filters.

The number of substrate supports may be less than twenty-five.

A substrate batch typically includes twenty-five substrates. In the example of a lithography apparatus, at least one substrate may always be present in a wafer handler of the lithography apparatus. Therefore, not all twenty-five substrates will be in the substrate storage module at the same time. Given this situation, the number of substrate supports in the substrate storage module may be less than the number of substrates in a batch (i.e., less than twenty-five). This advantageously reduces the size of the substrate storage module. Reducing the size of the substrate storage module can reduce the amount of time required to move from a first substrate support to a final substrate support, which in turn can increase the throughput of the lithography apparatus. Reducing the size of the substrate storage module can provide space for new components (e.g., vacuum systems and/or sensing systems).

The substrate storage module may include a ground conductor configured to reduce the risk of electrostatic discharge between substrates.

Electrostatic charges may build up in the substrate storage module, for example, on the substrate supports and/or the stored substrates. The ground conductor advantageously provides a safe outlet for the electrostatic discharge, thereby reducing the risk of electrical damage to the stored substrates and/or the substrate supports.

According to an embodiment of the present disclosure, a lithography apparatus configured to project a pattern from a patterning device onto a substrate is provided, which includes the substrate storage module of the first aspect.

The lithography apparatus may include: a vacuum substrate processing module, an atmospheric substrate processing module, and a transition substrate processing module disposed between the vacuum substrate processing module and the atmospheric substrate processing module. A substrate storage module may be located in the atmospheric substrate processing module.

According to a second aspect of the present disclosure, a method of storing a plurality of substrates in a controlled environment for protecting the substrates from ambient air is provided. The method includes using a vacuum system to individually clamp and release the substrates from a plurality of substrate supports.

The method may include using the vacuum system to detect the presence of the substrates in the plurality of substrate supports.

The method may include providing a gas flow across each substrate.

The gas may include filtered air.

Gases may contain low humidity.

Gases can include very clean, dry air.

The method may include providing a ground conductor to reduce the risk of electrostatic discharge between the substrates.

The method may include storing the substrates in a non-linear order.

A known substrate storage method involves storing substrates in a linear order. For example, a known substrate storage method involves storing a substrate in a first substrate support, then storing it in a second substrate support adjacent to the first substrate support, then storing it in a third substrate support adjacent to the second substrate support, etc. That is, a known method of storing six substrates involves storing the substrates in the following linear order of substrate supports: 1, 2, 3, 4, 5, 6. In this case, the distance between the first substrate (i.e., stored in substrate support 1) and the final substrate (i.e., in substrate support 6) is relatively large. By storing the substrates in a non-linear order (e.g., the following non-linear order of substrate supports: 1, 3, 5, 6, 4, 2), then the distance between the first substrate (i.e., stored in substrate support 1) and the final substrate (i.e., stored in substrate support 2) is reduced compared to known methods. This advantageously reduces the various distances required to store or remove each substrate compared to the extremes of known methods. This, in turn, can reduce undesirable movement of substrates.

According to an embodiment of the present disclosure, a method for lithographically exposing a plurality of substrates to form a stitched pattern on the substrates is provided. The method includes performing a first set of sub-exposures on a substrate to form a partially exposed substrate. The method includes storing the partially exposed substrate according to a second aspect of the present disclosure. The method includes repeating the first step and the second step for other substrates in the plurality of substrates. The method includes removing the partially exposed substrate from a storage and performing a second set of sub-exposures on the partially exposed substrate to form a substrate having a stitched pattern.

According to an embodiment of the present disclosure, a device is provided that is manufactured according to a method of lithographically exposing a plurality of substrates to form a spliced pattern on the substrates.

FIG1 schematically depicts a lithography system including a substrate storage module 30 according to the present disclosure. The lithography system comprises a radiation source SO and a lithography apparatus LA. The radiation source SO is configured to generate an extreme ultraviolet (EUV) radiation beam B. The lithography apparatus LA comprises an illumination system IL, a support structure MT configured to support a patterning device MA (e.g., a mask or a doubling mask), a projection system PS, and a substrate table WT configured to support a substrate W. The illumination system IL is configured to condition the radiation beam B before the radiation beam B is incident on the patterning device MA. The projection system PS is configured to project the radiation beam B (now patterned by the mask MA) onto a substrate W. The substrate W may include a previously formed pattern. In this case, the lithography equipment can align the patterned radiation beam B with the pattern previously formed on the substrate W.

The radiation source SO, the illumination system IL, and the projection system PS may all be constructed and configured so that they can be isolated from the external environment. A gas (e.g., hydrogen) at a pressure lower than atmospheric pressure may be provided in the radiation source SO. A vacuum may be provided in the illumination system IL and/or the projection system PS. A small amount of gas (e.g., hydrogen) at a pressure sufficiently lower than atmospheric pressure may be provided in the illumination system IL and/or the projection system PS.

The radiation source SO shown in FIG. 1 is of a type that may be referred to as a laser produced plasma (LPP) source. The laser 1, which may be, for example, a CO ₂ laser, is configured to deposit energy via a laser beam 2 into a fuel, such as tin (Sn), provided from a fuel emitter 3. Although tin is mentioned in the following description, any suitable fuel may be used. The fuel may, for example, be in liquid form and may, for example, be a metal or an alloy. The fuel emitter 3 may include a nozzle configured to guide tin, for example in the form of droplets, along a trajectory toward a plasma formation region 4. The laser beam 2 is incident on the tin at the plasma formation region 4. The deposition of the laser energy into the tin generates a plasma 7 at the plasma formation region 4. Radiation, including EUV radiation, is emitted from the plasma 7 during deexcitation and recombination of ions in the plasma.

EUV radiation is collected and focused by a near normal incidence radiation collector 5 (sometimes more commonly referred to as a normal incidence radiation collector). Collector 5 may have a multi-layer structure configured to reflect EUV radiation (e.g., EUV radiation having a desired wavelength, such as 13.5 nm). Collector 5 may have an elliptical configuration with two elliptical foci. As discussed below, the first focus may be at the plasma formation region 4 and the second focus may be at the middle focus 6.

The laser 1 may be separated from the radiation source SO. In this case, the laser beam 2 may be transferred from the laser 1 to the radiation source SO by means of a beam delivery system (not shown) comprising, for example, suitable guide mirrors and/or beam expanders and/or other optical devices. The laser 1 and the radiation source SO may be considered together as a radiation system.

The radiation reflected by the collector 5 forms a radiation beam B. The radiation beam B is focused at a point 6 to form an image of the plasma forming zone 4, which image serves as a virtual radiation source for irradiating the system IL. The point 6 at which the radiation beam B is focused may be referred to as an intermediate focus. The radiation source SO is arranged so that the intermediate focus 6 is located at or near an opening 8 in an enclosure 9 of the radiation source.

A radiation beam B is transmitted from a radiation source SO to an illumination system IL which is configured to condition the radiation beam. The illumination system IL may include a faceted field mirror device 10 and a faceted pupil mirror device 11. The faceted field mirror device 10 and the faceted pupil mirror device 11 together provide a radiation beam B having a desired cross-sectional shape and a desired angular distribution. The radiation beam B is transmitted from the illumination system IL and is incident on a patterning device MA held by a support structure MT. The patterning device MA reflects and patterns the radiation beam B. In addition to or instead of the faceted field mirror device 10 and the faceted pupil mirror device 11, the illumination system IL may include other mirrors or devices.

After reflection from the patterning device MA, the patterned radiation beam B enters the projection system PS. The projection system PS comprises a plurality of mirrors 13, 14 configured to project the radiation beam B onto a substrate W held by a substrate table WT. The projection system PS may apply a reduction factor to the radiation beam B, thereby forming an image having features that are smaller than corresponding features on the patterning device MA. For example, a reduction factor of four may be applied. Although the projection system PS has two mirrors 13, 14 in FIG. 1 , the projection system PS may include any number of mirrors (e.g., six mirrors).

The radiation source SO shown in Fig. 1 may include components not illustrated. For example, a spectral filter may be provided in the radiation source SO. The spectral filter may substantially transmit EUV radiation but substantially block radiation of other wavelengths, such as infrared radiation.

As discussed above, some lithography apparatuses may be used to perform a stitched lithography exposure, wherein at least two sub-exposures occur on adjacent areas of the substrate W to image a desired area of the patterning device MA onto the substrate W. FIG. 2 schematically depicts a maximum image area 20 of a first lithography apparatus compared to two maximum image areas 22, 24 of a second lithography apparatus. In the example of FIG. 2 , the maximum image area 22, 24 of the second lithography apparatus is half the maximum image area 20 of the first lithography apparatus. Whereas the first lithography apparatus requires one exposure 20 to image a desired area onto the substrate, the second lithography apparatus requires two sub-exposures 22, 24 to image the same desired area onto the substrate. In the case of a second lithography apparatus, a first sub-exposure 22 is performed using a first region of the patterning device, followed by a second sub-exposure 24 using a different region of the patterning device or using a different patterning device. The second sub-exposure 24 occurs on an adjacent region of the substrate such that the image formed on the substrate is equivalent to the image 20 formed using the first lithography apparatus. Other lithography apparatuses may have a smaller maximum image area than the second lithography apparatus. For example, the other lithography apparatus may have a maximum image area that is one-third of the maximum image area 20 of the first lithography apparatus. In this case, three sub-exposures may be performed such that the image formed on the substrate is equivalent to the image 20 formed using the first lithography apparatus.

After the lithographic exposure has been performed, the substrate may undergo an etchant treatment that may, for example, include a bake process. In the case of a stitched exposure, the bake process is delayed until each sub-exposure has occurred on all target areas of the substrate. In some lithographic processes, the bake process may not begin until all substrates in a batch of substrates (e.g., twenty-five substrates) have undergone stitched exposure. If the bake process occurs for an entire batch of substrates, a long delay (e.g., between five and ten minutes) may occur between performing a first set of sub-exposures on a first substrate in the batch and performing a final set of sub-exposures on a final substrate in the batch. The delay between performing an exposure and baking a substrate may adversely affect structures to be formed on the substrate, at least in part due to the interaction between the etchant on the substrate and the surrounding air in which the substrate is held. Generally speaking, the longer a lithographically exposed substrate is held in ambient air, the lower the quality of the structures formed on the substrate will be.

A method of reducing negative effects associated with ambient air interacting with a lithographically exposed substrate before the substrate undergoes an anti-etchant treatment includes providing a substrate storage module to the lithography apparatus for protecting the lithographically exposed substrate from the ambient air. FIG. 3 schematically depicts a top view of a portion of a lithography apparatus LA having a substrate storage module 30 according to the present disclosure. The portion of the lithography apparatus LA includes an atmosphere substrate handling module 32, a transition substrate handling module 34, and a vacuum substrate handling module 36. The atmosphere module 32 is configured to receive a substrate W from a coating development system (not shown) via a coating development system (track) interface 37 under clean room conditions (i.e., in ambient air with controlled contaminant levels), and to transfer the substrate W to the transition module 34. The transition module 34 is configured to receive the substrate W from the atmosphere module 32 under atmospheric conditions, to create a vacuum environment, and to provide the substrate W to the vacuum module 36. The transition module 34 includes doors 39a to 39d configured to form a seal when the transition module 34 converts its internal environment from atmospheric conditions to vacuum conditions, and vice versa. The transition module 34 includes stages 26a to 26b configured to hold the substrate when the transition between atmospheric conditions and vacuum conditions occurs. The vacuum module 36 is configured to hold the substrate W under vacuum conditions when the substrate W is used in the lithography apparatus LA (e.g., during measurement of the substrate and/or during lithography exposure of the substrate).

The atmospheric module 32 may include a substrate measurement stage 33 configured to measure characteristics such as, for example, the position and/or temperature of a substrate located on the substrate measurement stage 33. The substrate measurement stage 33 may be configured to perform additional functions such as, for example, to correct for positional offsets of a substrate (e.g., in cylindrical polar coordinates) and/or to thermally condition a substrate to a desired temperature. The vacuum module 36 may also include a measurement stage (not shown). The measurement stage 33 present in the atmospheric module 32 may be referred to as an atmospheric pre-aligner. The measurement stage present in the vacuum module 36 may be referred to as a vacuum pre-aligner. The atmospheric module 32 may include a coating development system interface 37. The coating and developing system interface 37 can be configured to provide an entrance to and/or an exit from the coating and developing system 38. The coating and developing system interface 37 and the coating and developing system 38 can include an entrance portion (not shown) for allowing a substrate to enter a lithography apparatus and an exit portion (not shown) for allowing a substrate to exit the lithography apparatus. For example, the coating and developing system 38 can provide the exiting substrate to an etchant treatment apparatus (not shown), which can be configured to receive a lithography-exposed substrate W and perform a baking process on the substrate. Additionally or alternatively, the resist treatment apparatus may be configured to coat a substrate W with a resist layer and provide the substrate to an entry portion of a coating and development system 38 and a coating and development system interface 37 to enter the lithography apparatus LA for lithography exposure. The atmospheric module 32 may include one or more storage units (not shown) configured to receive incoming substrates from the entry portion of the coating and development system interface 37 and/or provide exiting substrates to an exiting portion of the coating and development system interface 37. The atmospheric module 32 may include one or more robot arms 35a-35b. The robots 35a-35b may be configured to collect substrates from one or more storage units and/or provide substrates to one or more storage units. The robots 35a-35b may be configured to provide substrates W to and/or receive substrates from the substrate carrier 31, the substrate storage module 30, the transition module 34, and the coating and development system interface 37. Generally speaking, the substrate carrier 31 is used to store and transfer substrates for calibration and testing processes rather than lithography production. The robots 35a-35b may be configured to move substrates W between different parts of the atmospheric module 32 (e.g., moving substrates W between the substrate measurement stage 33 and the coating and development system interface 37).

The substrate storage module 30 can be an integral part of the lithography apparatus LA. That is, the substrate storage module 30 can remain connected to the lithography apparatus LA throughout the operation of the lithography apparatus LA (that is, the substrate storage module 30 cannot be removed from the lithography apparatus LA unless the lithography apparatus is disconnected). This is because the substrate storage module 30 is among the components of the lithography apparatus (e.g., the robot arms 35a to 35d), and it may be unsafe to attempt to access the substrate storage module 30 during the operation of the lithography apparatus LA. In the example of Figure 3, the substrate storage module 30 is an integral part of the atmosphere module 32. The substrate storage module 30 may be an integral part of the transition module 34, the vacuum module 36, or any other part of the lithography apparatus LA.

The substrate storage module 30 includes a controlled environment for protecting a plurality of substrates from the surrounding air. The substrate storage module 30 may be configured to store at least eighteen substrates. The substrate storage module 30 may be configured to store at least twenty substrates. When the substrate storage module 30 is an integral part of the atmosphere module 32, the substrate storage module 30 may have a gas delivery system configured to provide a gas having a desired chemical composition and humidity. When the substrate storage module 30 is an integral part of the vacuum module 36, the substrate storage module 30 may have a gas delivery system configured to provide a gas having a desired chemical composition and humidity. When the substrate storage module 30 is an integral part of the vacuum module 36 and the substrate storage module 30 includes a gas delivery system, the substrate storage module 30 may also include a door (e.g., an airlock) configured to seal the internal environment of the substrate storage module so that gas does not escape into the vacuum module 36.

Compared to the substrate storage module 30, the substrate carrier 31 is not an integral part of the lithography apparatus LA, because the substrate carrier 31 is temporarily connected to an external portion of the lithography apparatus LA and is configured to be easily attached to and detached from the lithography apparatus LA during operation of the lithography apparatus LA. The substrate carrier 31 may, for example, include a front-opening wafer transfer box (FOUP). The FOUP is used to transfer substrates between the lithography apparatus and the resist processing apparatus. The external environment of the FOUP 31 typically includes ambient air. Ambient air is also present in the internal environment of the atmosphere module 32. Although the ambient air present in the substrate carrier 31 and the atmosphere module 32 may be filtered and/or otherwise "cleaned" to clean room specifications, the ambient air may still have negative effects on substrates that have undergone lithographic exposure but are still about to undergo a bake process. Negative effects caused by the ambient air on the lithographically exposed substrates may be due to, for example, undesirable humidity levels and/or undesirable chemical composition (e.g., undesirable amine concentrations) of the ambient air. In contrast, the substrate storage module 30 includes a controllable environment for protecting a plurality (e.g., at least eighteen) of lithographically exposed substrates from the effects of the ambient air. For example, the temperature, humidity, and/or concentration of amines present in the gas provided to the substrate storage module 30 may be controlled.

FIG. 4 schematically depicts a front view of a substrate storage module 30 according to the present disclosure. The substrate storage module 30 is configured to store a plurality (e.g., at least eighteen) of substrates 40. The substrate storage module 30 may be configured to store less than an entire batch of substrates 40 (e.g., less than twenty-five substrates). For example, the substrate storage module 30 may be configured to hold twenty-four substrates 40 or less. This is because, although there are twenty-five substrates 40 in a batch, one or more substrates may be external to the substrate storage module 30 that interacts with other components of the lithography apparatus LA, such as being moved by robots 35a to 35d or measured on a metrology stage. In this case, the substrate storage module 30 can assist in the splicing exposure of the entire batch of substrates 40 while having a capacity less than the entire batch of substrates 40. In the example of FIG. 4 , the substrate storage module 30 is configured to store twenty-four substrates 40.

The substrate storage module 30 may be formed of materials such as, for example, metal, polycarbonate, and/or carbon-filled polyetheretherketone. The substrate storage module 30 may include a door and a mechanism (not shown) configured to actuate the door.

The substrate storage module 30 includes a plurality of substrate supports 42 for receiving substrates 40. The substrate supports 42 are stacked in a single column 44. In the example of FIG. 4 , the substrate storage module 30 is an integral part of an atmosphere module (not shown). The substrate supports 42 may be formed of a material having low electrical conductivity and may be electrically grounded to reduce the risk of unwanted discharge occurring in the substrate storage module 30.

The robot 35 of the atmosphere module is configured to receive an incoming substrate (e.g., from a vacuum module) and place the incoming substrate on an empty substrate support 42 in the substrate storage module 30. The robot 35 is also configured to pick up a departing substrate from a substrate support 42 of the substrate storage module 30 and remove the departing substrate from the substrate storage module 30. The substrate storage module 30 further includes an actuator 64 configured to move the substrate supports 42. The actuator 64 may be configured to move all substrate supports 42 simultaneously. The actuator 64 may, for example, include a movable rod 64 configured to move the substrate supports 42 along the support posts 44 in the z-direction, for example relative to the robot 35. The actuator 64 can move the substrate support, for example, at an acceleration of about 0.2 ms ^-2 or less. The actuator 64 can reduce or remove the extent of movement required of the robot 35. The actuator 64 can, for example, have a range of movement between about 500 mm and about 1000 mm, for example about 850 mm, along the z-direction. The robot 35 can then be configured to move along the x-direction and/or the y-direction and pick up a substrate 40 from a selected substrate support 42 by attaching the substrate 40 to the substrate stage 46 using the attachment mechanism 48. For example, the robot 35 can have a range of movement between about 300 mm and about 500 mm along the x-direction and/or along the y-direction. The robot 35 can then move the substrate 40 to, for example, a transition module 34 (see FIG. 3 ) in preparation for lithographic exposure in the vacuum module 36. It will be understood that the provision and reference to Cartesian coordinates in the figures is only to aid in understanding the figures, and that components of the lithography system (e.g., the robot 35) may operate using other coordinate systems (e.g., cylindrical coordinates).

The attachment mechanism 48 may, for example, include one or more suction cups or a mechanical or electrostatic clamp. Alternatively, the attachment mechanism 48 may include a material having a suitably high coefficient of friction for attaching the substrate to the substrate platform 46 when in contact with the substrate, such as Viton®. In the example of FIG. 4 , the attachment mechanism 48 includes two suction cups near the edge of the substrate platform 46. The suction cups 48 are configured to act on the lower surface of the substrate 40. The form of the attachment mechanism 48 may depend on the environment in which the robot 35 is configured to operate. For example, if the robot 35 is configured to operate under clean room conditions (e.g., in an atmosphere module), the attachment mechanism 48 may include a mechanical clamp or suction cup. Alternatively, if the robot 35 is configured to operate under vacuum conditions (e.g., in a vacuum module), the attachment mechanism 48 may include an electrostatic clamp.

The substrate storage module 30 includes a shield 50 located between adjacent slots 42. The shield 50 may, for example, include a metal sheet. In the example of FIG. 4 , the substrate storage module 30 includes a shield 50 between each adjacent substrate support 42. The shield 50 acts as a physical barrier to reduce the amount of debris transferred between the stored substrates 40. For example, when the robot 35 places a substrate 40 in a substrate support 42 and/or extracts a substrate 40 from a substrate support 42, some debris may be generated. The shield 50 reduces the amount of debris that may reach other substrates 40 stored in the substrate storage module 30 (e.g., the shield prevents debris from falling onto the lower stored substrate 40).

The substrate storage module 30 may include a gas delivery system 52. The gas delivery system 52 may operate in a manner similar to an air shower by providing a continuous gas flow 54 within the substrate storage module 30. The gas delivery system 52 is configured to provide a uniform gas flow 54 across each substrate support 42 within the substrate storage module 30. That is, the direction of the gas flow 54 is selected relative to the substrate support 42 so as to provide a uniform gas flow 54 across the exposure surface of each substrate 40 stored in the substrate storage module 30. The gas delivered to the substrate storage module 30 via the gas delivery system 52 may have a desired chemical composition and/or humidity. The gas 54 may include filtered air. The filtered air may include air having a particle cleanliness greater than that provided by ISO 14644 Class 1. The filtered air may include less than one particle per cubic meter, the particle having a size of about 0.1 µm or greater. The gas 54 may include low humidity. The gas 54 may have a humidity of about 50% or less. The gas 54 may have a humidity of about 30% or less. The gas 54 may have a humidity of about 10% or less. The gas 54 may have a humidity of about 7% or less. The gas 54 may have a humidity of about 1% or less. The gas 54 may have a humidity of about 0%. The gas 54 may include extremely clean dry air (XCDA). Very clean dry air may contain <1 ppbv TOCv, where TOCv represents total volatile organic compounds and ppbv represents parts per billion by volume. Very clean dry air may contain <1 ppbv TOCnv, where TOCnv represents total non-volatile organic compounds. Very clean dry air may contain <100 ppbv H ₂ O. Very clean dry air may have a particle cleanliness equal to or greater than ISO 14644 Class 2. For this purpose, the gas delivery system 52 may include a filter.

FIG5 schematically depicts a substrate storage module 30 according to the present disclosure. The substrate storage module 30 is suitable for use as an integral part of a lithography apparatus, such as the lithography apparatus LA of FIG1 . The substrate storage module 30 includes a controllable environment for protecting a plurality of (e.g., at least eighteen) substrates 110 from the surrounding air. In the example of FIG5 , the substrate storage module 30 includes twenty-five substrate supports 42. Each substrate support 42 is suitable for receiving one substrate 110. Thus, the substrate storage module 30 of FIG5 is suitable for receiving twenty-five substrates 110. Each substrate support 42 includes a vacuum clamp 120 configured to receive a substrate 110. The shape of the vacuum clamp 120 may correspond to the shape of the substrate 110 to be stored. 5, the substrate storage module 30 is configured to store circular substrates 110, and thus the vacuum chuck 120 is circular or ring-shaped. Other shapes may be used.

The substrate storage module 30 includes a gas delivery system 52 configured to provide gas flows 54 (only one flow is shown in FIG. 5 ) across the exposure surface (i.e., the upper surface) of the stored substrates 110. The gas delivery system 52 may include one outlet per substrate support 42 configured to direct the gas flow across each substrate 110. In the example of FIG. 5 , the gas delivery system 52 provides gas (e.g., air that may be delivered through filters in the gas delivery system 52) via a telescoping tube 190. The telescoping tube 190 allows the substrate support 42 to be moved up and down without interrupting the flow of gas to the gas delivery system 52. Electrical connections to the components of the substrate storage module 30 may be provided via dynamic cabling that allows the substrate support 42 to be moved up and down without interrupting the supply of electrical signals and/or power to the components of the substrate storage module 30 .

The substrate storage module 30 includes a vacuum system 100 fluidly coupled to the substrate support 42. The vacuum system 100 is configured to individually clamp and release substrates 110 to/from the substrate support 42. The vacuum system 100 may include a pneumatic vacuum mechanism. A vacuum clamp 120 is disposed at the center of the substrate support 42. The vacuum system 100 is fluidly coupled to the vacuum clamp 120 of the substrate support 42.

FIG6 schematically depicts an enlarged view of three vacuum fixtures 120 of the substrate support 42 of FIG5 . Each vacuum fixture 120 includes a first aperture 130 fluidly coupled to a first channel 140 and a second aperture 150 fluidly coupled to a second channel 160. Only the apertures 130, 150 and channels 140, 160 belonging to the uppermost vacuum fixture 120 are fully visible in FIG6 . The first channel 140 and the second channel 160 are fluidly coupled to the vacuum system 100 (visible in FIG5 ). The vacuum system 100 is configured to control the airflow within the channels 140, 160 and thereby control the actuation of the vacuum fixture 120. When a substrate (not shown in FIG. 6 ) is chucked to the substrate support 42, the vacuum system 100 may draw gas from the apertures 130, 150 along the channels 140, 160 and thereby generate a suction or vacuum force to chuck the substrate to the vacuum chuck 120. When releasing the substrate from the substrate support 42, the vacuum system 100 may provide gas (e.g., clean air) to the apertures 130, 150 through the channels 140, 160 to break the vacuum seal between the substrate and the vacuum chuck 120, thereby releasing the substrate from the vacuum chuck 120. Each vacuum chuck 120 may be individually actuated, thereby allowing each substrate to be chucked or released without affecting other stored substrates.

FIG. 7 schematically depicts an alternative configuration of a vacuum system 100 according to the present disclosure. In the example of FIG. 7 , the vacuum system 100 is configured on top of a column of a substrate support 42 (compared to the side configuration of FIG. 5 ). The vacuum system 100 includes a plurality of channels 200 fluidly coupled to a plurality of substrate supports 42. Each channel 200 is configured to control a vacuum fixture 120 of each substrate support 42. The vacuum system 100 may include at least one channel 200 per vacuum fixture 120. The vacuum system 100 includes a valve manifold 210 configured to control airflow along each channel 200 and thereby individually control the clamping and release of each vacuum fixture 120. The valve manifold 210 may include at least one valve per channel 200. For example, if the substrate storage module 30 includes twenty-four substrate supports 42, the valve manifold 210 may include twenty-four valves. Each valve may be individually controlled so that the substrates 110 may be individually vacuum clamped to and released from the substrate supports 42. The valve manifold 210 may include dual stable valves. The dual stable valves advantageously provide continued clamping of any clamped substrates 110 in the event of a failure of the vacuum system 100. The dual stable valves may be electronically actuated. The valve manifold 210 may be fluidly coupled to a vacuum apparatus (not shown) via a valve manifold conduit 220.

The vacuum system 100 includes a sensing system 230 configured to detect the presence of a substrate 110 in a plurality of substrate supports 42. That is, the sensing system 230 is configured to determine whether a substrate support 42 in a substrate storage module 30 is occupied by a substrate 110. The sensing system 230 may include one or more pressure sensors in fluid communication with the channel 200. In the example of FIG. 7 , the sensing system 230 includes a pressure sensor manifold 240 that includes a plurality of pressure sensors. The pressure sensor manifold 240 may include at least one pressure sensor per substrate support 42. For example, if the substrate storage module 30 includes twenty-four substrate supports 42, the sensing system manifold 240 may include twenty-four pressure sensors. At least one pressure sensor may be in fluid communication with each channel 200. The presence or absence of a substrate on each substrate support 42 may be determined individually by a corresponding pressure sensor determining the presence or absence of a vacuum at each vacuum clamp 120. If the pressure sensor detects the presence of a vacuum, it may be determined that the substrate 110 is clamped by the vacuum clamp 120 and is therefore present on the substrate support 42. If the pressure sensor detects the absence of a vacuum, it may be determined that the substrate is not present on the substrate support 42. The pressure sensor manifold 240 may be fluidly coupled to a vacuum apparatus (not shown) via a pressure sensor manifold conduit 250. Each pressure sensor in the pressure sensor manifold 240 may, for example, provide a signal to a processor (not shown) indicating whether a substrate support 42 is occupied by a substrate 110. The processor may be configured to receive the signal from the sensing system 230 and control movement of the actuator 64 and/or the robot 35 depending on the signal received from the sensing system 230 so that the robot 35 only places an incoming substrate 110 in an unoccupied substrate support 42.

The substrate storage module 30 may include a ground conductor 260 configured to reduce the risk of electrostatic discharge between the stored substrates 110. For example, the ground conductor 260 may include a metal grid or a conductive filter. The ground conductor 260 may be configured to discharge the gas flow 54 provided by the gas delivery system 52 and swept across the exposure surface of the stored substrates 110. The ground conductor 260 may be located downstream of the gas filter so that gas particles that become charged by interacting with the filter are discharged by the ground conductor 260 before being provided through the exposure surface of the stored substrate 110.

Referring again to FIG. 5 , each substrate support 42 includes a coating configured to reduce friction between the substrate support 42 and the substrate 110 supported by the substrate support 42. In the example of FIG. 5 , the coating is provided on portions of the vacuum chuck 120 that are configured to contact the stored substrate 110 (e.g., the raised inner and outer rings of the vacuum chuck 120 shown in FIG. 6 ). For example, the coating may include diamond-like carbon. The coating is used to reduce friction between the substrate 110 and the substrate support 42, thereby reducing the risk of defects (e.g., substrate backside defects) and/or the risk of contamination through frictional interactions.

The substrate supports 42 are configured to be individually removable from the substrate storage module 30. The substrate storage module 30 may include an attachment mechanism configured to couple and decouple the substrate supports 42 from the substrate storage module 30. For example, the substrate supports 42 may be inserted into slots formed in the support posts 44 or the support arms 170, and the attachment mechanism may be actuated to secure the substrate supports 42 in place. The attachment mechanism may include any suitable reversible connection member, such as, for example, a pin and socket configuration, a detent connector, a clip, a latch, a bayonet connector, a magnetic retention member, etc. Having individually removable substrate supports 42 allows each substrate support 42 to be removed for maintenance (e.g., cleaning) or disposal without damaging the other substrate supports 42. For example, a substrate support 42 may be defective, in which case a user may remove the defective substrate support from the substrate storage module 30 and replace the defective substrate support with a spare functional substrate support 42. As another example, a substrate support 42 may require maintenance (e.g., cleaning), in which case a user may remove the substrate support from the substrate storage module 30 for cleaning and/or fixing before reinserting the substrate support. The plurality of substrate supports 42 may be configured to be individually replaceable, such as in a manner similar to a cassette.

A method of storing a plurality of (e.g., at least eighteen) substrates in a controlled environment for protecting the substrates from ambient air includes using a vacuum system (e.g., vacuum system 100 of FIGS. 5-7 ) to individually clamp and release substrates from a plurality of substrate supports (e.g., substrate supports 42 of FIGS. 5-7 ). The method may include using the vacuum system 100 to detect the presence of a substrate in the plurality of substrate supports 42. For example, the pressure sensor manifold 240 of FIG. 7 may be used to determine the presence or absence of a substrate on a substrate support 42. The method may include providing a gas flow 54 through each substrate 110. For example, the gas delivery system 52 of FIGS. 4-7 may be used to provide a uniform gas flow 54 through an exposure surface of each substrate 110. The gas may include filtered air. The gas may include low humidity. The gas may include very clean dry air. The method may include providing a grounded conductor to reduce the risk of electrostatic discharge between substrates 110. For example, the metal grid 260 of Figure 7 can be used to discharge the gas flow 54 provided by the gas delivery system 52 before providing the gas flow 54 through the exposure surface of the substrate 110.

The method may include storing substrates in a non-linear order. Known substrate storage methods involve storing substrates in a linear order. For example, known substrate storage methods involve storing a substrate in a first substrate support, then storing it in a second substrate support adjacent to the first substrate support, then storing it in a third substrate support adjacent to the second substrate support, etc. For example, a known method of storing six substrates involves storing the substrates in the following linear order of substrate supports: 1, 2, 3, 4, 5, 6. In this example, the distance between the first substrate (i.e., stored in substrate support 1) and the final substrate (i.e., in substrate support 6) is relatively large. By storing the substrates in a non-linear order (e.g., storing six substrates in the following non-linear order of substrate supports: 1, 3, 5, 6, 4, 2), the distance between the first substrate (i.e., stored in substrate support 1) and the final substrate (i.e., stored in substrate support 2) is reduced compared to known methods. This advantageously reduces the various distances required to store or remove each substrate compared to the extremes of known methods. This, in turn, can reduce undesirable movement of substrates.

FIG8 is a flow chart showing a method for exposing a plurality of substrates to form a stitched pattern on the substrates according to aspects of the present disclosure. The first step (a) of the method includes performing a first set of sub-exposures on a substrate to form a partially exposed substrate. For example, referring to FIG3 , a substrate W may be retrieved from a coating and development system interface 37 (e.g., via a storage unit) by a robot 35a and placed on a substrate measurement stage 33. Characteristics such as, for example, position and/or temperature of the substrate W may be measured by the substrate measurement stage 33. The robot 35b may then retrieve the substrate W from the substrate measurement stage 33 and place the substrate in a transition module 34. The transition module 34 may create a vacuum environment before a robot 35c in the vacuum module 36 picks up the substrate W from the transition module 34. In the case of a dual stage lithography apparatus, the robot 35c may then place the substrate W on a substrate table on a metrology stage (not shown) within the vacuum module 36. The metrology stage may be configured to measure characteristics of the substrate W, such as, for example, the position of alignment features of the substrate and/or the configuration of the substrate. The robot 35d may then exchange the substrate table from the metrology stage with the substrate table from the exposure stage, such as the substrate table WT depicted in FIG. 1 . A first set of sub-exposures may then occur while the substrate W is held by the substrate stage.

Referring again to FIG. 8 , the second step (b) of the method includes moving the partially exposed substrate to a substrate storage module that includes a controlled environment, a plurality of substrate supports, and a vacuum system fluidly coupled to the plurality of substrate supports, the vacuum system being configured to individually grip and release the substrates. For example, referring to FIG. 3 , robot 35 d may pick up a partially exposed substrate W from a substrate stage (not shown) and place the partially exposed substrate in transition module 34. Transition module 34 may then replace the vacuum environment with the ambient environment. Robot 35 a may then pick up the partially exposed substrate from transition module 34 and place the partially exposed substrate on a substrate support of substrate storage module 30. The substrate storage module 30 can be configured to store at least eighteen substrates. The substrate storage module 30 can be an integral part of the lithography apparatus. Alternatively, the substrate storage module 30 can be an integral part of the vacuum module 36 (see FIG. 3 ).

Referring again to FIG. 8 , the third step (c) of the method includes repeating the first step (a) and the second step (b) for a predetermined number of substrates. That is, the subsequent substrate undergoes a first set of sub-exposures to become a partially exposed substrate before being moved to a substrate storage module for protection from ambient air and vacuum clamping. The predetermined number of substrates may correspond to a number of substrates that is less than the total number of substrates in the batch. This is because the first substrate may have been unloaded from the substrate storage module while the final substrate is undergoing the first sub-exposure. That is, not all substrates may undergo the first sub-exposure before the partially exposed substrate is removed from the substrate storage module for undergoing the second sub-exposure. Steps (a) and (b) may be repeated for substrates in the batch that have not undergone the first set of sub-exposures. The fourth step (d) of the method includes removing the partially exposed substrate from the substrate storage module and performing a second set of sub-exposures on the partially exposed substrate to form a substrate having a stitched pattern. The second set of sub-exposures occurs using a different patterning device or a different portion of the same patterning device. That is, the pattern imparted to the substrate in the second set of sub-exposures is different from the pattern imparted to the substrate in the first set of sub-exposures. For example, referring to Figure 3, the partially exposed substrate can be retrieved from the substrate storage module 30 by the robot 35b and placed in the transition module 34. The transition module 34 can create a vacuum environment before the robot 35c in the vacuum module 36 retrieves the partially exposed substrate from the transition module 34. In the case of a dual-stage lithography apparatus, the robot 35c may then place the partially exposed substrate on a substrate table on a measurement stage (not shown) within the vacuum module 36. The measurement stage may be configured to measure characteristics of the partially exposed substrate. The robot 35d may then exchange the substrate table from the measurement stage with the substrate table from the exposure stage, such as the substrate table WT depicted in FIG. 1 . A second set of sub-exposures may then occur to form a substrate having a stitched pattern. It will be appreciated that a stitched lithography exposure process may involve performing more than two sets of sub-exposures on a plurality of substrates. Thus, the method may include storing and removing partially exposed substrates in a wafer storage module more than once during an entire stitched lithography exposure process.

Referring again to FIG. 8 , the optional fifth step of the method includes moving the substrate having the stitched pattern out of the lithography apparatus. The optional sixth step (f) of the method includes performing a baking process on the substrate having the stitched pattern. For example, referring to FIG. 3 , the substrate having the stitched pattern can be moved from the vacuum module 36 through the transition module 34 by the robot arms 35 a to 35 d, and placed on the coating development system interface 37 in the atmosphere module 32 (e.g., via a storage unit). The robot arm (not shown) in the anti-etching agent processing apparatus can capture the substrate having the stitched pattern from the coating development system 38, and place the substrate in the anti-etching agent processing apparatus so that the baking process can be performed on the substrate. Alternatively, if the resist treatment equipment is not available, the substrate with the stitched pattern can be returned to the substrate storage module 30 to be protected from the ambient air until it can undergo the resist treatment. In contrast, the substrate carrier 31 will hold the substrate in the ambient air.

Although the use of the lithography apparatus LA including the substrate storage module 30 has been described in the context of storing substrates 40 to be subjected to stitching lithography exposure, the lithography apparatus LA including the substrate storage module 30 can be used for other types of lithography exposure. For example, the substrate storage module 30 can be used to store a single exposed substrate until the resist treatment apparatus is ready to receive the single exposed substrate.

The substrate storage module 30 may form part of a metrology apparatus. The metrology apparatus may be used to measure the alignment of a projected pattern formed in an resist on a substrate relative to a pattern already present on the substrate. This measurement of relative alignment may be referred to as overlay. The metrology apparatus may, for example, be positioned adjacent to a lithography apparatus LA and may be used to measure overlay before the substrate (and resist) have been processed. The substrate storage module 30 may, for example, be used to store lithography exposed substrates in a controlled environment before the substrates are provided to the metrology apparatus for measurement. As another example, substrates configured for use in calibrating a metrology apparatus may be stored in the substrate storage module for rapid access when required.

Although aspects of the present disclosure may be specifically referenced herein in the context of lithography apparatus, aspects of the present disclosure may be used in other apparatus. Aspects of the present disclosure may form part of a metrology apparatus or any apparatus that measures or processes an object such as a wafer (or other substrate). Such apparatus may be generally referred to as a lithography tool. Such lithography tools may use vacuum conditions or ambient (non-vacuum) conditions, with the substrate storage module comprising a controlled environment that protects the substrate from the surrounding air.

The term "EUV radiation" may be considered to cover electromagnetic radiation having a wavelength in the range of 4 nm to 20 nm, for example in the range of 13 nm to 14 nm. EUV radiation may have a wavelength less than 10 nm, for example a wavelength in the range of 4 nm to 10 nm, such as 6.7 nm or 6.8 nm.

Although FIG1 depicts the radiation source SO as a laser produced plasma LPP source, any suitable source may be used to generate EUV radiation. For example, EUV emitting plasma may be generated by using a discharge to convert a fuel (e.g. tin) into a plasma state. This type of radiation source may be referred to as a discharge produced plasma (DPP) source. The discharge may be generated by a power supply, which may form part of the radiation source or may be a separate entity connected to the radiation source SO via electrical connections.

Although specific reference may be made herein to the use of lithography apparatus in IC manufacturing, it should be understood that the lithography apparatus described herein may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic resonance memory, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, etc.

Although the above may specifically refer to the use of substrate storage modules in the context of optical lithography, it will be understood that the substrate storage modules may be used in other applications, such as imprint lithography, and are not limited to optical lithography where the context permits. In imprint lithography, the configuration in the patterning device defines the pattern produced on the substrate. The configuration of the patterning device may be pressed into a layer of resist supplied to the substrate, where the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. The patterning device is removed from the resist after the resist has cured, thereby leaving the pattern therein.

Aspects of the present disclosure may be implemented in hardware, firmware, software, or any combination thereof. Aspects of the present disclosure may also be implemented as instructions stored on a machine-readable medium that can be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form that can be read by a machine (e.g., a computing device). For example, a machine-readable medium may include read-only memory (ROM), random access memory (RAM), disk storage media, optical storage media, flash memory devices, electrical, optical, acoustic, or other forms of propagation signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others. In addition, firmware, software, routines, instructions may be described herein as performing certain actions. However, it should be understood that this description is only for convenience and that the actions are actually caused by a computing device, processor, controller, or other device that executes the firmware, software, routines, instructions, etc.

Although specific aspects of the present disclosure have been described above, it will be appreciated that the substrate storage module and method of storing substrates may be practiced in other ways than those described. The above description is intended to be illustrative and not restrictive. Therefore, it will be apparent to those skilled in the art that the described aspects of the present disclosure may be modified without departing from the scope of the claims set forth below.

1: Laser 2: Laser beam 3: Fuel emitter 4: Plasma formation zone 5: Near normal incidence collector/collector 6: Intermediate focus/point 7: Plasma 8: Opening 9: Enclosure 10: Faceted field mirror device 11: Faceted pupil mirror device 13: Mirror 14: Mirror 20: Maximum image area/image 22: Maximum image area/first sub-exposure 24: Maximum image area/second sub-exposure 26a: Stage 26b: Stage 30: Substrate storage module 31: Substrate carrier/front-opening cell gate 32: Atmospheric substrate handling module/atmospheric module 33: Substrate measurement stage 34: Transition substrate handling module/transition module 35: Robotic arm 35a: Robotic arm 35b: Robotic arm 35c: Robotic arm 35d: Robotic arm 36: Vacuum substrate handling module/vacuum module 37: Coating and developing system interface 38: Coating and developing system 39a: Door 39d: Door 40: Substrate 42: Substrate support/slot 44: Single column/support column 46: Substrate platform/substrate edge platform 48: Attachment mechanism/suction cup 50: Shielding element 52: Gas delivery system 54: Airflow/gas 64: Actuator/movable rod 100: Vacuum system 110: Substrate/round substrate 120: vacuum fixture 130: first aperture 140: first channel 150: second aperture 160: second channel 170: support arm 190: telescopic tube 200: channel 210: valve manifold 220: valve manifold pipeline 230: sensing system 240: pressure sensor manifold 250: pressure sensor manifold pipeline 260: ground conductor/metal grid (a): first step B: radiation beam (b): second step (c): third step (d): fourth step (f): sixth step IL: illumination system LA: lithography equipment MA: patterning device MT: support structure PS: Projection system SO: Radiation source W: Substrate WT: Substrate table

Embodiments of the invention will now be described by way of example only with reference to the accompanying schematic drawings, in which: - FIG. 1 schematically depicts a lithography system according to the present disclosure comprising a lithography apparatus, a radiation source and a substrate storage module. - FIG. 2 schematically depicts a maximum image area of a first lithography apparatus compared to two maximum image areas of a second lithography apparatus. - FIG. 3 schematically depicts a top view of a portion of a lithography apparatus having a substrate storage module according to the present disclosure. - FIG. 4 schematically depicts a front view of a substrate storage module according to the present disclosure. - FIG. 5 schematically depicts a substrate storage module according to the present disclosure. - FIG. 6 schematically depicts an enlarged view of three vacuum clamps of the substrate support of FIG. 5. -  FIG. 7 schematically depicts a substrate storage module including an alternative configuration of a vacuum system for individually clamping and releasing substrates according to the present disclosure. -  FIG. 8 shows a flow chart of a method for exposing a plurality of substrates to form a stitched pattern on the substrates according to the present disclosure.

30: Baseboard storage module

42: Baseboard support

52: Gas delivery system

54: Airflow

100: Vacuum system

110: Substrate/round substrate

120: Vacuum clamp

170: Support arm

190: Telescopic tube

Claims (15)

A substrate storage module for use as an integral part of a lithography apparatus comprises: a controllable environment for protecting a plurality of substrates from ambient air; a plurality of substrate supports for receiving the substrates; and a vacuum system fluidly coupled to the plurality of substrate supports, the vacuum system being configured to individually grip and release the substrates. A substrate storage module as claimed in claim 1, wherein the plurality of substrate supports include a coating configured to reduce friction between the plurality of substrate supports and the substrates. A substrate storage module as claimed in claim 2, wherein the coating comprises diamond-like carbon. A substrate storage module as claimed in claim 1 or claim 2, wherein the plurality of substrate supports are configured to be individually removable from the substrate storage module. The substrate storage module of claim 1 or claim 2, wherein the vacuum system comprises a sensing system configured to detect the presence of the substrates in the plurality of substrate supports. The substrate storage module of claim 1 or claim 2, comprising a gas delivery system configured to provide a gas flow through each substrate support within the substrate storage module. A substrate storage module as claimed in claim 6, wherein the gas comprises filtered air. A substrate storage module as claimed in claim 6, wherein the gas contains low humidity. A substrate storage module as claimed in claim 7, wherein the gas comprises extremely clean dry air. A substrate storage module as claimed in claim 1 or claim 2, wherein the number of substrate supports is less than twenty-five. A substrate storage module as claimed in claim 1 or claim 2, comprising a grounded conductor configured to reduce the risk of electrostatic discharge between the substrates. A lithography apparatus configured to project a pattern from a patterning device onto a substrate, the lithography apparatus comprising a substrate storage module as claimed in any one of claims 1 to 11. The lithography apparatus of claim 12 comprises a vacuum substrate processing module, an atmospheric substrate processing module and a transition substrate processing module disposed between the vacuum substrate processing module and the atmospheric substrate processing module, wherein the substrate storage module is located in the atmospheric substrate processing module. A method of storing a plurality of substrates in a controlled environment for protecting the substrates from ambient air includes using a vacuum system to individually clamp and release the substrates from a plurality of substrate supports. A method for lithographically exposing a plurality of substrates to form a stitched pattern on the substrates, the method comprising the following steps: (a)    performing a first set of sub-exposures on a substrate to form a portion of an exposed substrate; (b)    storing the portion of the exposed substrate according to the method of claim 14; (c)    repeating steps (a) and (b) for other substrates in the plurality of substrates; and (d)    removing the portion of the exposed substrates from the storage and performing a second set of sub-exposures on the portion of the exposed substrates to form a substrate having a stitched pattern.